Some businesses can not ship a product unless a recipient is of a legal age. In this case the only possible automated solution is to have your OpenCart user to upload an identification (ID) so that customer support could match the age and shipping address to ensure the product is not being purchased underage.
Is there such an automated solution (a plug in) where your first time user would be required for upload an ID into an OpenCart user account for manual verification (verification is done once unless the shipping details change)?